Association of Sulfur, Transition Metals, and the Oxidative Potential of Outdoor with Acute Cardiovascular Events: A...

We do not currently understand how spatiotemporal variations in the composition of fine particulate air pollution [fine particulate matter with aerodynamic diameter $$ ($$)] affects population health risks. However, recent evidence suggests that joint concentrations of transition metals and sulfate may influence the oxidative potential (OP) of $$ and associated health impacts.

The purpose of the study was to evaluate how combinations of transition metals/OP and sulfur content in outdoor $$ influence associations with acute cardiovascular events.

We conducted a national case-crossover study of outdoor $$ and acute cardiovascular events in Canada between 2016 and 2017 (93,344 adult cases). Monthly mean transition metal and sulfur (S) concentrations in $$ were determined prospectively along with estimates of OP using acellular assays for glutathione ($$), ascorbate ($$), and dithiothreitol depletion ($$). Conditional logistic regression models were used to estimate odds ratios (OR) [95% confidence intervals (CI)] for $$ across strata of transition metals/OP and sulfur.

Among men, the magnitudes of observed associations were strongest when both transition metal and sulfur content were elevated. For example, an OR of 1.078 (95% CI: 1.049, 1.108) (per $$) was observed for cardiovascular events in men when both copper and S were above the median, whereas a weaker association was observed when both elements were below median values ($$, 95% CI: 1.007, 1.031). A similar pattern was observed for OP metrics. $$ was not associated with acute cardiovascular events in women.

The combined transition metal and sulfur content of outdoor $$ influences the strength of association with acute cardiovascular events in men. Regions with elevated concentrations of both sulfur and transition metals in $$ should be examined as priority areas for regulatory interventions. https://doi.org/10.1289/EHP9449.